Numerous types of vehicles are frequently used on terrain over which it is difficult for pneumatic tires to operate. Both military vehicles, such as tanks and other armoured vehicles, and civilian vehicles, such as tractors, forest and construction machinery and recreational vehicles, are sometime utilized on terrains which are very soft, for example sand and snow surfaces. Generally, pneumatic tires are not capable of efficient operation on such surfaces as they tend to burrow into the surface rather than riding across the surface.
In order to provide vehicles which could efficiently travel over soft surfaces, vehicles using endless track have been developed.
Originally, the tracks used on such tracked vehicles were made of a plurality of metallic links pivotally attached to each other in order to form an endless track. These tracks were, and still are, very heavy, and they generally cause serious damage to the roads and other surfaces over which they run and also generally result in an uncomfortable ride for the passengers. Some heavier vehicles, such as large excavators, still use metal tracks.
Hence, conventional metallic tracks have the disadvantages of being noisy and vibration prone, not sufficiently durable and/or not usable on road surfaces. Accordingly, substantial efforts have been made to construct quieter, smoother operating and more durable tracks for tracked vehicles.
In order to solve the problems caused by metallic tracks, elastomeric tracks have been developed and proposed in recent years. With the combination of elastomeric technology and a tremendous amount of trial and error, various types of elastomeric tracks are now available in the industry.
Elastomeric tracks are generally formed around a basic carcass or belt. The carcass includes a generally endless belt-shaped elastomeric member, a number of core bars (usually of metal, fiberglass or carbon fiber) embedded therein and aligned in the longitudinal direction thereof and extending in traverse directions thereof, and steel cords (tension-resistant members) embedded in the endless elastomeric member to surround the core bars circumferentially outwardly. Examples of such elastomeric tracks can be seen in U.S. Pat. Nos. 4,904,030 (Ono), 5,295,741 (Togashi et al.), 5,511,869 (Edwards et al.) and 6,241,327 (Gleasman).
However, the advent of elastomeric tracks has created another problem. Metallic tracks of the prior art had many disadvantages that current elastomeric tracks have generally solved such as damage to paved roads and noise. Metallic tracks had however the advantage to have a better grip or traction on icy and other flat and slippery surfaces. Indeed, the metallic cleats or grousers of these metallic tracks could “eat” into the ice in order to move. Elastomeric tracks do not have cleats and their ground-engaging lugs cannot “eat” into ice and thus, present some difficulties when driven on icy and other slippery surfaces.
Though there have been proposed solutions to the aforementioned problem, for example, the anti-skid system proposed in European Patent No. 1 518 719 (Kess), there is still a need for a device that can improve the traction of elastomeric tracks especially when the vehicle is traveling on icy and/or other slippery surfaces.